Since getting my Toyota Prius a couple of years ago, I've become a bit of a car-maintenance priss. One of the ideas frequently asked about on the Prius Web sites has to do with exchanging the standard Toyota drain plug for a magnetic type. The idea is, I gather, that this magnet will "grab up" all the little bits of metal shaved off of the cylinders and other engine components during routine use, but which would then act as an abrasive to accelerate wear and tear. I suspect that the oil filter is specifically designed to grab this stuff up, but others argue that the magnet is necessary to more rapidly grab and hold these bits. Any thoughts? -- Evan

TOM: Evan, don't you have enough to worry about in your life?

RAY: A magnetic drain plug is a cute idea, and it does what it purports to do. I just don't believe it's terribly necessary.

TOM: First of all, not much stuff gets shaved off the engine components. If you see a lot of metal shavings in your oil, it's time to trade in your car.

RAY: Plus, there is the oil filter, which grabs anything larger than about 40 microns -- or about twice the size of my brother's brain.

TOM: Any shavings or particles that get through the oil filter are generally so small that they're of no real significance. And every 5,000 miles, you just drain them out during your regular oil change anyway.

RAY: So if you like playing with magnets, then by all means, put a magnetic drain plug in your Prius. It won't hurt anything. But it's not going to provide much, if any, additional protection for your engine.